Priority is claimed from Republic of Korean Patent Application No. 99-60549 filed Dec. 22, 1999, which is incorporated in its entirety by reference.
1. Field of the Invention
The invention relates generally to a method of forming a storage node in a semiconductor device. More particularly, the present invention relates to a method of forming a storage node in a semiconductor device capable of forming a conductive film storage node in a vertical structure, by forming a hard mask used to form a noble metal storage node using a TiN film deposited on an oxide film and over said oxide film.
2. Description of the Prior Art
In a semiconductor device, the capacitance of a capacitor may be represented as a value proportional to the dielectric constant of a dielectric film between the surface area of an electrode and an electrode as shown in Equation 1.
C=∈A/dxe2x80x83xe2x80x83[Equation 1]
where ∈ indicates a dielectric constant, A indicates the surface area and d indicates the thickness of a dielectric film.
Therefore, in the process of manufacturing a semiconductor device that is gradually fined, in order to secure a capacitance more than a given amount by which the semiconductor device can be properly operated, various methods by which a storage node is formed in a three dimensional structure to increase the surface area of the storage node or a high dielectric material such as BST having a high dielectric constant is used to secure a capacitance, etc. have been researched. As complicated process is required in order to form a storage node having a three-dimensional structure, however. there is a problem that the throughput is lowered since the manufacturing cost is increased and the number of the process is increased. Also, if the BST high dielectric is used, there is a problem the leakage current characteristic is degraded since it is difficult to strictly maintain an oxygen stoichiometry. Further, in case of a capacitor using BST as a dielectric film, a noble metal such as Pt having a large anti-oxidization, etc. must be used. However, this material has the problems that not only it is difficult to be etched since it is very stable but also it is difficult to obtain a vertical profile since etching is performed by physical sputtering.
Therefore, conventionally, in order to obtain a vertical profile, a method by which a hard mask is formed of TiN or oxide film in order to etch Pt and etching is performed using the mask at high temperature has been attempted. However, the method has drawbacks that the scattering effect of ions could be used because the hard mask formed of TiN could not be formed at high height in view of deposition characteristic and the hard mask formed of the oxide film is eroded during etching process since it has a poorer selective ratio than the hard mask formed of TiN.
It is therefore an object of the present invention to provide. a method of forming a storage node in a semiconductor device by which a storage node of a vertical profile can be formed, using a mask that can solve the problems of the conventional hard mask formed of TiN or oxide film.
In order to accomplish the above object, a method of forming a storage node in a semiconductor device according to the present invention is characterized in that it comprises the steps of forming an interlayer insulating film on a semiconductor substrate in which a given structure is formed; after forming a contact hole through a given region of the semiconductor substrate is exposed by etching a given region of the interlayer insulating film, forming a plug burying the contact hole; sequentially forming a conductive film and an oxide film on the entire structure; after patterning the oxide film. forming a TiN film on the oxide film and thus forming a hard mask of an oxide film and TiN film structure; patterning the conductive film by etching process using the hard mask to form a storage node; and removing the hard mask.